Heavy gluino as the lightest supersymmetric particle

We consider the possibility that the lightest supersymmetric particle is a heavy gluino. After discussing models in which this is the case, we demonstrate that the g-LSP could evade cosmological and other constraints by virtue of having a very small relic density. We then consider how neutral and charged hadrons containing a gluino will behave in a detector, demonstrating that there is generally substantial apparent missing momentum associated with a produced g-LSP. We next investigate limits on the g-LSP deriving from CERN, LEP, LEP2 and run I Fermilab Tevatron experimental searches for excess events in the jets plus missing momentum channel and for stable heavily ionizing charged particles. The range of mg that can be excluded depends upon the path length of the g in the detector, the amount of energy it deposits in each hadronic collision, and the probability for the g to fragment to a pseudo-stable charged hadron after a given hadronic collision. We explore how the range of excluded mg depends upon these ingredients, concluding that for non-extreme cases the range 3;GeV approx-lt mg approx-lt 130 endash 150; GeV can be excluded at 95% C.L. based on currently available OPAL and CDF analyses. We find that run II at the Tevatron can extend the excluded region (or discover the g) up to mg ∼ 160 endash 180; GeV. For completeness, we also analyze the case where the g is the NLSP (as possible in gauge-mediated supersymmetry breaking) decaying via g → g+gravitino. We find that the Tevatron run I data exclude mg ≤240; GeV. Finally, we discuss application of the procedures developed for the heavy g-LSP to searches for other stable strongly interacting particles, such as a stable heavy quark. copyright 1999 The American Physical Society